选用桥梁单元的刚度下降率作为损伤因子.基于铁路列车-桥梁耦合振动模型,计算桥梁在线振动响应对损伤因子的灵敏度并构建灵敏度矩阵,以结构不同状态下的响应残差为约束条件建立灵敏度方程,用Tikhonov正则化方法求解灵敏度方程得到各单元的损伤因子,实现对桥梁损伤的定位和定量评估.应用该识别方法对简支梁桥和2跨连续梁桥的识别结果表明:该识别方法对测点位置不敏感.可根据梁上任意1个测点的响应准确确定损伤位置及损伤程度;不但能识别桥梁的绝对损伤,而且能识别桥梁的损伤增量,即相对损伤;抗噪能力较强,即使噪声水平达到10%,也能正确识别出5%以上的损伤,但对5%以下小幅损伤可能会有误判.%The stiffness reduction ratio of the bridge element is used as a damage index. Based on the train-bridge coupling vibration model, the sensitivities of bridge online vibration responses to the damage indices are computed and the sensitivity matrix is constructed. Using the responses differences between different states as the constraint condition, the sensitivity equation is established and solved with the Tikhonov regularization method to get the element damage indices, so that the bridge damage can be located and quantified. The identification results of a simply-supported bridge and a two-span continuous bridge indicate that the proposed damage identification method is insensitive to the measurement point locations and the response of any measurement point on the bridge can be used to locate and quantify the damage correctly. It can identify not only the absolute damage of the bridge but also the bridge damage increment, i.e. , the relative damage. The proposed method has rather good stability against measurement noise because damage more than 5％ can be well identified even the noise level is up to 10％. However, the small damage less than 5％ may be misjudged sometimes.
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